Thermic switch



y 9, 3 E. c. RANEY 1,907,666

THERMIC SWITCH Filed Aug. 9. 1929 r1r: z 1 1 E 90 1'1 l 1 e1 6 -3 thebody portion of the fixed contact. The that protrude from the ends ofthe V-shaped Patented May 9, '1933 UNITED STATES PATENT OFFICE ESTEL c.RANEY, OF COLUMBUS, OHIO .THERMIC SWITCH Application tiled August a,1929. Serial No. 384,577.

The invention particularly provides a portion 9 is embedded in the endwall of thermic switch that may be formed of parts the part 2 of thehead, .The' portion 9 has that may be made at a low cost of 'producatitsend edges a plurality of serrations 1O lion and set for etlicientoperation of the which securely lock the fixed contact in the switch atdefinite temperatures. insulating material of which the head is Theinvention may be contained in formed. The terminals 6 are formednarswitches that vary in their details and, to ilrower tha n thecontacts .5. They protrude lustrate a practical application of theinvenfrom the head whereby the terminals may tion, I have selected aswitch containing the be inserted 1n the end of a plug for connect- 10invention as an example of the various eming the switch to an externalcircuit. bodiments of my invention and shall de- The movable contact 15of the switch is scribe it hereinafter. -The particular strucformed of apair of plates 16 that are conturc selected, as an example, is shown inthe nected together for pivotal movements one acctimpanyin c drawing.relative to the other. Preferably, the con- Fig. 1 illustrates avertical section of the tiguous ends of the plates 16 are locatedswitch. Fig. 2 is a view of a section taken in recesses of a part of aswitch actuating on the plane of the line 2-2 indicated in member andsprings 17 are connectedto ears Fig. 1.- Fig. 3 illustrates a verticalsection 18 located at the outer corners of the plates of a part of theswitch taken on a plane at 16. The springs 17 operate to produce a 5right-angles to the plane of the section of thrust or pressurecomponents-in the planes Fig. 1. Fig. 4 is a composite view ofparts ofthe plates 16 towards each other and latoi' the switch. indicating theassembly of eral components that tend to angularly move su ch parts.Fig. 5 is a perspective view of the plates 16 relative to each other. Cop a fixed contact of the SWltClL. Fig. 6 is a tacting pressure betweentheouter ends of view of a sectioutaken on the plane of the the plates16 and the arcuate edges of the line 66 as indicated in Fig. 1. fixedcontacts 5 is produced when the lateral The instrun'ient illustrated inthe drawcomponents are in one direction and when ingis provided with ahead of insulating the lateral components are in the opposite dimaterialthat contains the switch, and a rection the plates 16 move from thefixed stem, that is connected to the head, which contacts 5. Preferably,the end edges of the contains the thermic material that operates plates16 are curved and the ears 18 pmthe switch. Thejhead 1 is formed of twotrude from the corners of the plates in the parts 2 and 3 that may beinterconnected by line ofthe .curvature of the end edges. The means ofthe threaded portions 4. The fixed length of the fixed contacts 5 aresubstancontacts 5 of the switch are provided with tially the same as thelength of the curved the electric terminals 6 for connecting the edges0t the plates 16 between the ears, fixed contacts with an externalcircuit. The whereby a compact arrangement of the parts fixed contacts 5are provided with curved is provided for locating the switch withinflange portions 7 that extend-substantially a cylindrical head which hasa relatively at right-angles to the body portions 8 of the smalldiameter and yet provides a large confixed contacts. The flangedportions are. tact area between the contacts of-the switch. curved on acenter. located substantially in The movable contact 15 isconnected tothe .axis of the instrument. --T he edges of an actuating member'bymeans of a pair the flanged portions 7 form the contacting of sheetmetal strips 20. The strips 20 have arcasof the switch. Each contact 5is also portions bent to form V-shaped channel provided with a portion 9that extends subportions 21 having a length substantially the stantiallyparallel to the direction in which same as the width of the bodyportions of the flange 7 extends, but in a direction oppothe plates 16.The ends of thechannel site to that in which the flange extends fromportions 21 are provided with lugs 22 channels 21 and are bent so as tocover or enclose the corners of the inner ends of the plates 16 whenthey are inserted in the V-shaped channels. The strips 20 are so placedthat the channel openings of the strips extend in opposite directions.They are secured in this position, when assembled, by means of a pair ofdiscs 25 and 26. Preferably, the strips 20 are provided with tongues 27having a width narrower than the body portion of the strips 20 and thediscs 25 and 26 are provided with slots that fit the tongues 27 whenthey are placed side by side, so that when the discs 25 and 26 areforced over the tongues 27, they will securely bind the strips 20together.

The movable contact 15, together with its connecting member, issupported for movements relative-to a plate 30 that is secured in thehead 1 between the parts 2 and 3 of the head. The plate 30 -is diepressed to shape and there is formed in the plate 30 raised V-shapedportions 31. For purposes of securing the plate 30 in position, andinsuring registration of the protruding portions 31 of the plate 30,-.rela- I tive to the fixed contacts, the part 20f the shell may beprovided with a suitable recess 32 and the plate 30 may be provided witha tongue 33 that, substantially fits the recess 32. The plate 30 is alsoprovided with a slot 34 "that-is located between, and extends parallelto, the ridges 31. The slot 34' has a size substantially the same asthat of the cross section of the strips 20, when they are placed back toback, to permit free movements of the strips 20 through the slot 34 ofthe plate 30.

The plate 30 is located in a plane substantially parallel to the planeof the contact edges of the fixed contacts 5. This locates the plane ofthe tops of the ridges parallel to the plane of the contacts andpreferably the parts are so formed that these planes are in closeproximity to each other and the ridges are placed close to the axisoftheinstrument or about midway between the axis of the instrument and thefixed contacts.. The tops of the ridges 31 are therefore locatedintermediate the points of connection of the ends of the springs withthe plates 16 and the inner ends of the plates and comparatively closeto the axis of the instrument. In the operations of the movable contact15, by the springs 17, the protruding ridges 31 of the plate 30 coact toproduce a wide opening of the contacts andan early closingof thecontacts in thef movement of the actuating member that operates theswitch through the connecting member formed by the strips 20. When theinner ends of the plates pass through the plane of the fixed contacts,the outer endsof the plates will be moved away from the fixed contactsand so as to strike the ridges 31 of the plate 30. The points ofconnection of the ends ofthe springs 17 being located on the outside ofthe ridges, the springs tend to draw the outer ends of the platestowards each other as the plates pivot on the tops of the ridges 31 Inthe reverse movement of the actuating member, the plates will tilt onthe ridges 31, moving the'outer ends of the plates 16 towards thecontact edges of the fixed contacts by a relatively short movement ofthe connecting strips 20, and until the inner ends of the plates 16 passthrough and contraction of atherniic element, the

expansion movements operating on the movable contact member to break thecircuit through the contacts and a compression spring operating on themovable contact, as

the element contracts, to complete the circuit through the contacts. Athimble 40,

. formed of insulating material, is located in an opening formed in theend'wall of the part. 3 of the shell, 1 and' is reciprocally movabletherein. A cup 41is located in the thimble 40. The cup 41 has a flange42 that rides on the edge of the thimble 40. The flange is skirted toprovide a recess for receiving the end ofac'onvolutc spiral spring 43located between the flange 42 and the plate 30. The plate 30 has acentrally raised portion to form a seat'44 for the larger end of theconvolute spring 43. The convolute spring enables relatively free-moveinerit of the turns of the spring and causes the return movementsof'ends of the plates 16.

The bottom of the cup 41 is located in spaced relation to the bottom ofthe thimble 40-and a-compression spring 45 is located within the cup 41and intermediate the disc 25 and the bottom of the cup. The lower endsof the strips 20 extend through a slot formed in the bottom of the cupand the disc 26 is located beneath the bottom of the cup 41 and ismovable between the limits provided by the bottom of the cup 41 and thebottom of the thimble 40. When, therefore, the thimble 40 is moved bythe expansion of the thermic element, it compresses the spring 45against the vertieal component induced at the inner ends of the plates-.16 by the tension of the springs 17. The

spring 45 is compressed until the disc 26 engages the bottom of thethimble 40. Continued upward movement of the thimble 40 moves the strips20 and the inner ends of the contact plates 16 until the lateral component induced by the spring 17 is' less than the pressure produced bythe spring, 45. At this point the lateralcomponent, however, issufficiently great for a good contact pressure between the contacts ofthe switch. The lateral component at the outer ends of the contactplates 16, which is the pressure applied at the ends of the movablecontact against the fixed contact, is greater than the lateral componentat the inner ends .of the plates by reason of the relative location ofthe connecting points of the springs 17. When this contact pressurediminishes to a certain point, which, however, is still suflicientlygreat to maintain a good contact pressure, the spring 45 will cause theinner ends of the plates to snap through the plane of the contact edgesof the contacts 5 and the lateral components of the spring 17 will bereversed which will operate to raise the disc from the bottom of thethimble 40 and to separate the contacts as the central portions of theplates strike the ridges 31 of the plate 30. When the thermic elementcontracts, the thimble 40 is moved downwardly by the spring 43 and theinner ends of the plates 16 will immediately move downwardly by reasonof the interengagement of the disc 26 on the bottom of the cup 41. Thecontact plates tilt on the ridges 31 and quickly raise the outer ends ofthe plates above the plane of the tops of the ridges 31 and reverse thelateral components produced by the springs 17, to cause a. quickconnection by a very short reverse movement of the inner ends of theplates 16.

The spring 43 operates to maintain the thimble 40 in contact with asheet metal bellows 50 located in a metal sleeve 51 that protrudes fromthe end wall of the part 3 of the shell 1. The sleeve 51 is providedwith outwardly turned ears 52 which anchor the sleeve 51 in theinsulating material of the shell 1. The thimble 40 is located in one endof the sleeve 51 and is moved therein by the expansion bellows 50 or thespring 43 when the bellows contracts. Preferably, the thimble 40 isprovided with a recess 54 for receiving the tip 53 of the expansionbellows which operates to maintain the upper end of the bellows in axialalignment in the instrument.

The lower end of the bellows 50 is connected to a shell 55. The interiorof the bellows 50 communicates with the interior of the shell 55 and thetwo are filled with a suitable thermic material that has, preferably, alarge coefficient of expansion.

Fluids, such as water or mixtures of liqu ds,

or plastics, that melt or solidify at substantially definitetemperatures, may be used.

Preferably materials, or mixtures of,materials, are used that atdefinite temperature points have increasing coefiicients of expansion.The points at which their physical condition changes may be varied byforming mixtures of definite proportions of the materials, in the mannerwell known in the art. In the particular form of construction shown inthe drawing, the bellows 50 and the shell 55 are filled With a mixtureof water and alcohol in a desired proportion. The water and alcoholmixture is particularly advantageous by reason of the fact that itaffords a reliable and definiteexpansion point at which the movablecontact may be operated and thus insures certainty of operation at thesame point in the succeeding operations of the refrigerating apparatuscontrolled by the switch. In the operation of refrigerating apparatus,the water will freeze and portions of the frozen ice will subsequentlymelt to cause corresponding changes in movement ofthe movable contact bythe movement of the bellows containing the mixture, which will produce areliable operation of the switch when a definite portion of the Waterhas changed physically. Consequently, the switch will, in its repeatedoperation, always operate at the same thermic or temperature point. Thebellows 50, being located within the sleeve 51, it is, by reason of theair space between the bellows and the sleeve, shielded to a certainextent from the transmission of heat therefrom, while the shell 55 is ina more d rect heat conductive relation, with reference to exteriorbodies and, consequent- 1y, heat is more readily transmitted to and fromthe shell 55 than to and from the bellows. The shell 55 is not onlyconnected to the bellows 50, but is also. connected to the end of thesleeve 51. Preferably, the ends of the sleeve 51 and the shell 55 arethreaded to enable adjustment of the bellows with reference to themovable contact in order to bring about operation of the switch at thedesired times. Thus the material within the bellows and the shell maybe, if de-v sired, raised or lowered to the desired temperature at whichthe switch is to be opened and, upon insertion of the bellows within thesleeve 51, the shell may be threaded into the sleeve 51 until the switchis tripped open, whereupon the shell and the sleeve may be secured inthis adjusted relation by either soldering or reaming, or any othersuitable interlocking means. In the form shown. the shell is provided wth a channel 56 and the end of the sleeve 51 is spun or forced into thechannel 56 so as to seal and interlock the sleeve 51 to the end of theshell 55 in this adjusted relation.

The thermic material is introduced into the bellows and the shell 55through the con- -tracted end 57 that is closed by means of the plug 58.Solder 59 may be placed on the end of the shell so as to cover and sealthe end of the shell.

The end 57 of the shell 55 is tapered so as to form between the plug 58and the surfaces of the tapered end, a space for the thermic materialthat conforms to a cylindrical punch having a central openmg and a sharpknife edge. The part that conforms to the knife edge is locatedintermediate the flaring inner surface of the tapered wall of the end 57and the surface of the plug 58 which protrudes well into the interior ofthe shell. The 'thermic material that thus surrounds the plug, andlocated within the tapered wall, is surrounded by and contains withinitself a relatively large amount of metal which has high heatconductivity and, since the material between these highly conductiveparts is thinned down to a sharp edge or line, the temperature of thethermic material at this point will be substantially the same as that ofthe outside atmosphere contiguous to the tip of the shell and, by reasonof the tapered walls or flaring surfaces that extend from a line on thesaid surfaces, crystallization or solidification will leadily set up insuch a chamber or space and thus bring about prompt solidification orcrystallization in the body of the shell.

The shell 55 is also provided with a heat distributor for conducting andtransmitting the heat from the wall of the shell throughout the materiallocated in the central portion of the shell. A sheet metal corrugatedmember 60, having a length substantiall the same as the shell, islocated therein. t has portions in contact with the surface of the wallof the shell and portions located in proximity to the axis of the shellwhereby heat will be readily transmitted through the member to and fromthe wall of the shell into that portion of the material located wellwithin the shell and more or less remote from the wall' of the shell.Preferably, the heat conductor 60 is provided with a plurality oftapered tongues 61 that extend towards the bellows 50 which reduces theconductivity of the member at the end of the shell that is connected tothe bellows. This rovides a means that insures the solidification of thethermic material within the shell 55 in advance of solidification of thematerial within the bellows 50. The bellows is also shielded by thesleeve 51, while the shell 55 is rovided with heat conductive walls andt e interior member 56 aids in the ready absorption or transmission ofheat from the thermic material in the shell and the earlycrystallization and solidification of the thermic material therein. Theexpansion occurring thereby is transmitted to the non-solidifiedmaterial in the shell and bellows which causes the bellows to expand andeventually operate the switch.

I claim:

1. In a switch, a pair of fixed contacts, a. pair of movable platesadapted to make contact with the fixed contacts at their ends, a pair ofsheet metal members having V- shaped channel parts for receiving theends of the plates for maintaining the ends of the lates in position, apair of springs for pro ucing an end thrust of the plates against thebottoms of the channels of the a pair of sheet metal members havlng-V-shaped channels at its end for receiving ends of the plates for movingthe said ends of the plates through the plane of the contacting surfacesof the said fixed contacts and to force the said sheet, metal membersagainst each other.

3. In a switch, a pair of fixed contacts, a movable contact formed of apair of plates, a pair of springs connected to end portions of theplates for producing an endwise thrust in the plates towards each otherand lateral components towards and away from the fixed contacts. a thirdplate formed of sheet metal, the said third plate having ridges struckup therefrom, a channel member for receiving the inner ends of the firstnamed plates and movable through the said third plate for moving theinner ends of the first named plates across the plane of the contactingsurfaces of the said fixed contacts and the plane of the tops of thesaid ridges.

4. In a switch, a pair of fixed contacts, a movable contact formed of apair of plates, a pair of springs connected to end portions of theplates for producing an endwise thrust in the plates towards each otherand lateral components towards and away from the fixed contacts, a.third plate formed of sheet metal, the said third plate having ridgesstruck up therefrom, the said last named plate having a recessedportion, a

movable member having a skirt portion and.

a convolute spring located intermediate the skirt portion and therecessed portion of the second named plate, a channel member operativelyconnected to the movable member and to the inner ends of the first namedplates for moving the said plates through the plane of the contacts andthe plane of the ridges.

5. In a switch, a pair of fixed contacts, a movable contact comprising apair of plates adapted to electrically connect the fixed contacts, apair of springs connected to end portions of the plates for producing anend thrust in the plates towards each other and lateral pressurecomponents towards and away from the contacts, a movable member foractuating the inner ends of the plates and comprising a cup, a channeledmember for receiving the inner ends of the plates and extending throughthe bottom of the cup, 2. spring located intermediate the bottom of thecup, and connected to the channel member for moving the inner ends ofthe plates through the plane of the fixed contacts.

6. In a switch, a pair of fixed contacts, a movable contact comprising apair of lates adapted to electrically connect the fixe contacts, a pairof springs connected to end portions of the plates for reducing an endthrust in the plates towar s each other and lateral pressure componentstowards and away from the contacts, a movable member for actuating theinner ends of the plates and comprising a cup, a channeled member forreceiving the inner ends of the plates and extending through the bottomof the cup, a spring located intermediate the bottom of the cup andconnected to the channel member for moving the inner ends of the platesthrough the plane of the fixed contacts, a third late formed of sheetmetal and having ri ges struck up therefrom, the ridges locatedintermediate the line of movement of the inner ends of the plates andthe ends of the plates, the last named plates having a recess foryieldingly resisting the movement of the cup, and a convolute springhaving an end portion for fitting the said recess, the said clup havinga skirt portion for receiving the other end of the convolute spring.

7. In a switch, a pair of fixed contacts, a movable contact comprising apair of members adapted to electrically connect the fixed contacts, apair of sprin s connected to the end portions of the mem ers forproducing an end thrust in the members towards each other and lateralpressure components towards or away from the contacts, a plate having apair of ridges, the plane of the ridges being located parallel to and inclose proximity to the plane of the said fixed con tacts, theridgesbeing located opposite the points between the contacts and inclose proximity to the line of movement of the inner ends of themembers, a movable thermic element responsive in its movements tochanges of temperature, means for interconnecting the thermic elementwith the inner ends of the said members and comprising a pair ofchanneled strips for receiving the inner ends of the members, and a cupconnected to the strips, the cup and strips having means for producinglimited free movements of the strips relative to the cup, a compressionspring connected to the strips and to the'cup for yieldingly resistingthe movement of the strips relative to the cup, a compression springlocated intermediate the cup and the plate for causing return movementsof the inner ends of the members upon return movement of the thermicelement.

In witness whereof I have hereunto signed my name to this specification.

- ESTEL C. RANEY.

